Endometrial ablation is a procedure conducted to reduce or eliminate excessive uterine bleeding by ablating the innermost lining of the uterus, known as the endometrium. One method of ablating the endometrium is by using the HydroThermAblator® System (HTA) which circulates heated fluid in the uterus. A sheath is inserted into the uterus via the cervix to introduce and circulate the heated fluid and to maintain a target ablation temperature through the uterus. An ablation sheath generally includes an inlet lumen via which the heated fluid is introduced into the uterus and a return lumen via which the fluid may be returned, heated and circulated back into the body to maintain the target ablation temperature.